This invention relates to a biomedical electrode for the measurement of bioelectric potentials.
In order to record and interpret electrocardiographic, encephalographic, and other bioelectric phenomena, it is essential to use appropriate biomedical electrodes. In recent years, the requirements in clinical rehabilitation and for physiological studies have increasingly called for uninterrupted electrocardiographic and other recordings of the subjects without restraint upon their freedom in daily life. For these purposes there is an eager demand for highly efficient and yet lightweight and inexpensive biomedical electrodes.
Among the existing biomedical electrodes, relatively excellent in performance are those of the button type. (Refer, e.g., to Japanese Patent Application Publication No. 46849/1981.) In FIG. 1, a commercially available biomedical electrode of the button type is digrammatically shown as comprising a metallic electrode button 1, an electrode sensor 2, an artificial skin adapter 3 (a fabric, paper, or plastic sheet) held between the button and sensor, and an artificial skin 4 (a sponge sheet or the like impregnated with an electrolyte or in a gelled state or the like) secured to the electrode sensor and adapter on one side and adapted to fit the human skin on the other side. Terminals of a measuring circuit not shown are connected to the button 1 by sockets, clips or the like not shown. The sensor 2 consists of a plastic base and an electrically conductive film of silver=silver chloride composite material or the like covering the base surface. The plastic base is employed for the sensor 2 to resist the corrosive attack of the electrolyte and also to replace the expensive metals usually used to make the sensors.
A drawback of the plastic-based sensor is that its flange is not strong enough to hold the adapter 3 firmly in place. If adequate strength is to be attained, the flange must have increased wall thickness. A thicker flange, however, would objectionably protrude if the adapter were thin, causing the artificial skin to bulge accordingly and rendering it infeasible to make intimate contact with the electrode sensor and the human skin, as indicated in FIG. 2. An attempt to remove this drawback might be to use a thicker adapter 3 and embed the flange partly in it as well as in the artificial skin. However, the arrangement would mar the total flexibility of the artificial skin and again make its intimate contact with and adhesion to the human skin impossible. In view of these, there is a strong demand for a biomedical electrode in which both the flange of the sensor 2 and the adapter 3 are as thin as possible while the flange retains adequate strength.
This invention aims at providing an electrode sensor which takes a firm hold of the adapter and comes in intimate contact with and attains good adhesion to the skin.